目录：
1. Select查询表时阻塞
表可能被锁。
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7 | mysql> show OPEN TABLES where In_use > 0;
+--------------+-----------------+--------+-------------+
| Database | Table | In_use | Name_locked |
+--------------+-----------------+--------+-------------+
| demodatabase | demo_table_1234 | 1 | 0 |
+--------------+-----------------+--------+-------------+
1 row in set (0.00 sec)
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这时候显示表 demo_table_1234 已被使用
2. 查看RDS系统资源
查看RDS系统资源
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5 | #查看性能指标，累计值
mysqladmin -hlocalhost -uroot extended-status
#查看性能指标，1秒内差值
mysqladmin -hlocalhost -uroot extended-status --relative --sleep=1
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3. 修改密码的几种方法
方法1: SET PASSWORD命令
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2 | mysql -u root
mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('newpass');
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方法2: mysqladmin
1 | mysqladmin -u root password "newpass"
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如果root已经设置过密码，采用如下方法
1 | mysqladmin -u root password oldpass "newpass"
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方法3: UPDATE user
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4 | mysql -u root
mysql> use mysql;
mysql> UPDATE user SET Password = PASSWORD('newpass') WHERE user = 'root';
mysql> FLUSH PRIVILEGES;
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方法4: 丢失root密码时
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4 | mysqld_safe --skip-grant-tables&
mysql -u root mysql
mysql> UPDATE user SET password=PASSWORD("new password") WHERE user='root';
mysql> FLUSH PRIVILEGES;
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